This invention relates to the support of brake shoes in a spot-type disc brake and to the associated brake shoes. A spot-type disc brake of the type with which the present invention is related is shown in German Published Patent Application DE-OS No. 38 33 553. In this type of brake it is possible to remove the brake shoes radially outwards from an open, radially extending cavity of the brake housing, without the brake housing having to be dismantled or swung out of position. The circumferential forces ensuing upon a brake application are transmitted by the brake shoes to axial brake housing projections provided with plane supporting surfaces which face the cavity in the circumferential direction and whereon the brake shoes rest. Holding pins are provided in order to secure the brake shoes against being displaced in the radial direction, the holding pins axially extending across the radially outer area of the cavity and being detachably fastened on the brake housing. The pad carrier plates of the brake shoes have projections with openings for receiving the holding pins. A spring detachably fastened in the area of the holding pins presses the brake shoes radially against the holding pins so as to prevent the brake shoes from rattling. The spring and the holding pins have to be removed for the purpose of removing the brake shoes.
This known spot-type disc brake has the disadvantage that in manufacturing the brake housing, considerable relatively complicated milling work has to be performed when machining the above-mentioned plane supporting surfaces for the brake shoes. The guideway and the fastening device of the brake shoes on the holding pins likewise require a considerable amount of manufacturing and assembling operations.
In another spot-type disc brake known from German published Patent Application DE-OS No. 14 75 288, supporting surfaces of circular arc shape are provided for the brake shoes, these surfaces not being milled but rather turned together with the cylinder bores of the four brake cylinders. The brake shoes are supported on the supporting surfaces both in the radial in the and circumferential directions. This solution, however, has the disadvantage that it is impossible to remove the brake shoes radially outwards. It is necessary to dismantle the brake housing for the purpose of replacing the brake shoes which causes additional assembly operations and costs incurred thereby. It is an object of this invention to provide a spot-type disc brake where the brake shoe supporting surfaces destined for receiving the circumferential forces can be turned together with the bore of the brake cylinder but where it is possible to radially remove the brake shoes through a radially outwards open brake housing cavity.